Abstract:

A gas-generating apparatus (10) includes a reaction chamber (18)
containing a solid fuel component (24) and a liquid fuel component (22)
that is introduced into the reaction chamber by a fluid path, such as a
tube, nozzle, or valve. The flow of the liquid fuel to the solid fuel is
self-regulated. Other embodiments of the gas-generating apparatus are
also disclosed.

Claims:

1. A gas-generating apparatus comprising:a reaction chamber containing a
solid fuel precursor;a reservoir containing a liquid fuel precursor;a
fluid path for introducing the liquid fuel precursor into the reaction
chamber; anda means for controlling the introduction of a predetermined
portion of the liquid fuel precursor, which portion is less than all of
the liquid fuel precursor, to the solid fuel precursor in the reaction
chamber.

2. A gas-generating apparatus comprising:a reaction chamber containing a
solid fuel precursor;a reservoir containing a liquid fuel precursor; anda
fluid path for introducing the liquid fuel precursor into the reaction
chamber, wherein a predetermined portion of the liquid fuel precursor,
which portion is less than all of the liquid fuel precursor, is
introduced to the solid fuel precursor in the reaction chamber in
response to a pressure within the reaction chamber.

3. The gas-generating apparatus of claim 2, wherein the reaction chamber
is a movable chamber disposed between the reservoir and an empty chamber.

4. The gas-generating apparatus of claim 3, wherein the fluid path
comprises a nozzle disposed in a sidewall of the movable chamber.

5. The gas-generating apparatus of claim 4, wherein the nozzle comprises a
valve.

6. The gas-generating apparatus of claim 4, wherein the nozzle comprises
an opening.

7. The gas-generating apparatus if claim 4, wherein the movable chamber is
biased toward the reservoir.

8. The gas-generating apparatus of claim 2, wherein the reaction chamber
is connected to a fuel transfer valve by a flexible tube.

9. The gas-generating apparatus of claim 2, wherein the movable chamber is
connected to an arm.

10. The gas-generating apparatus of claim 9, wherein the arm is configured
to extend into the reservoir so that when the movable chamber is moved,
the arm seals the fluid path.

11. The gas-generating apparatus of claim 9 further comprising a wheel
connecting the movable chamber to the arm and a stopper operatively
connected to the arm, wherein the stopper seals the fluid path when the
chamber is moved.

12. The gas-generating apparatus of claim 11, wherein the stopper is
movably disposed within a tube hingedly connected to the arm and hingedly
and fluidly connected to the fluid path, wherein the stopper moves to
seal the fluid path when the chamber is moved.

13. The gas-generating apparatus of claim 2, wherein the fluid path
comprises a tubular member having a free end extending into the reaction
chamber, wherein at least one port is disposed in the free end, and
wherein the solid fuel precursor and a wicking material are connected to
the free end.

15. The gas-generating apparatus of claim 13 further comprising a fluid
control valve disposed within the tubular member and a pressure transfer
tube connecting the reaction chamber and the tubular member so that the
fluid control valve may be triggered by the pressure within the reaction
chamber.

16. The gas-generating apparatus of claim 2, wherein the reaction chamber
comprises an expandable bladder containing both the solid fuel precursor
and the liquid fuel precursor, and wherein the fluid path is formed in a
sleeve which separates the solid fuel precursor from the liquid fuel
precursor, and wherein the liquid fuel precursor is in contact with the
solid fuel precursor so that a reaction occurs between the liquid fuel
precursor and the solid fuel precursor to produce a gas when the
expandable bladder is in a collapsed configuration, and wherein the
liquid fuel precursor is not in contact with the solid fuel precursor so
that substantially no gas is produced when the expandable bladder has
been inflated to a predetermined diameter.

17. The gas-generating apparatus of claim 16, wherein the
expandable-bladder is in the collapsed configuration when the pressure in
the reaction chamber is below a predetermined level so that additional
gas is produced, and wherein the expandable bladder is inflated when the
pressure in the reaction chamber is above a predetermined level.

18. The gas-generating apparatus of claim 16 further comprising a fluid
transfer path configured to transfer the gas produced by the reaction to
a fuel cell.

19. The gas-generating apparatus of claim 2 further comprising:a mesh
piston slidably disposed within the reaction chamber in contact with the
solid fuel precursor, wherein the mesh piston is configured to allow a
by-product of a reaction between the solid fuel precursor and the liquid
fuel precursor to pass therethrough;a flexible tube extending through the
mesh piston, wherein the flexible tube is the fluid path; anda spring
biasing the mesh piston toward the solid fuel precursor.

20. The gas-generating apparatus of claim 19, wherein the spring pushes
the mesh piston through the by-product to a location of fresh solid fuel
precursor as solid fuel precursor is consumed by the reaction.

21. The gas-generating apparatus of claim 2 further comprising a piston
slidably disposed between the reaction chamber and the reservoir, wherein
the fluid path comprises a small-bore tubular member that extends through
the piston.

22. The gas-generating apparatus of claim 21 further comprising a sprag
disposed within the reaction chamber and adjacent to the piston, wherein
the sprag is configured to allow the piston to move only toward the
reservoir.

23. The gas-generating apparatus of claim 21 further comprising a bladder
disposed within the reservoir, wherein the bladder is configured to
expand in order to expel the liquid fuel precursor from the reservoir.

25. The gas-generating apparatus of claim 21, wherein the tubular member
is sized and dimensioned to prevent the liquid fuel precursor from
flowing through the tubular member until a threshold pressure
differential between the reservoir and the reaction chamber is achieved.

26. The gas-generating apparatus of claim 2, wherein the reservoir is a
deformable bladder with a constant force spring fixedly attached to a
first end of the bladder, wherein the constant force spring continuously
pull the first end of the bladder toward a second end of the bladder to
expel the liquid fuel precursor through the fluid path.

27. The gas-generating apparatus of claim 26 further comprising a
pressure-triggered sleeve, wherein the pressure-triggered sleeve is
configured to prevent the REPLACEMENT SHEET constant force spring from
winding when the pressure in the reaction chamber reaches a threshold
pressure.

28. The gas-generating apparatus of claim 26, wherein the fluid path
comprises a nozzle fluidly connected to the bladder.

29. The gas-generating apparatus of claim 28, wherein the nozzle includes
a single exit port.

30. The gas-generating apparatus of claim 28, wherein the nozzle includes
a plurality of exit ports.

32. The gas-generating apparatus of claim 31, wherein each of the multiple
flow paths has a different diameter.

33. The gas-generating apparatus of claim 32, wherein the diameters of the
multiple flow paths decrease sequentially while a chamber provided
beneath the multiple flow paths increases in diameter sequentially.

34. The gas-generating apparatus of claim 31, wherein each of the multiple
flow paths is provided with a valve, wherein the valve is configured to
restrict access to its associated flow path until a threshold pressure is
achieved.

[0002]The invention relates generally to fuel supplies for fuel cells. In
particular, the invention relates to fuel cartridges for fuel cells
configured to produce a fuel gas on demand.

[0003]Fuel cells are devices that directly convert chemical energy of
reactants, i.e., fuel and oxidant, into direct current (DC) electricity.
For an increasing number of applications, fuel cells are more efficient
than conventional power generation, such as combustion of fossil fuel, as
well as portable power storage, such as lithium-ion batteries.

[0005]Compressed hydrogen is generally kept under high pressure and is
therefore difficult to handle. Furthermore, large storage tanks are
typically required and cannot be made sufficiently small for consumer
electronic devices. Conventional reformat fuel cells require reformers
and other vaporization and auxiliary systems to convert fuels to hydrogen
to react with oxidant in the fuel cell. Recent advances make reformer or
reformat fuel cells promising for consumer electronic devices. The most
common direct oxidation fuel cells are direct methanol fuel cells or
DMFC. Other direct oxidation fuel cells include direct ethanol fuel cells
and direct tetramethyl orthocarbonate fuel cells. DMFC, where methanol is
reacted directly with oxidant in the fuel cell, is the simplest and
potentially smallest fuel cell and also has promising power application
for consumer electronic devices. SOFC convert hydrocarbon fuels, such as
butane, at high heat to produce electricity. SOFC requires relatively
high temperature in the range of 1000° C. for the fuel cell
reaction to occur.

[0006]The chemical reactions that produce electricity are different for
each type of fuel cell. For DMFC, the chemical-electrical reaction at
each electrode and the overall reaction for a direct methanol fuel cell
are described as follows:

[0007]Half-reaction at the anode:

CH3OH+H2O→CO2+6H++6e.sup.

[0008]Half-reaction at the cathode:

1.5O2+6H+6e.sup.-→3H2O

[0009]The overall fuel cell reaction:

CH3OH+1.5O2→CO2+2H2O

[0010]Due to the migration of the hydrogen ions (H+) through the PEM
from the anode to the cathode and due to the inability of the free
electrons (e.sup.-) to pass through the PEM, the electrons flow through
an external circuit, thereby producing an electrical current through the
external circuit. The external circuit may be used to power many useful
consumer electronic devices, such as mobile or cell phones, calculators,
personal digital assistants, laptop computers, and power tools, among
others.

[0011]DMFC is discussed in U.S. Pat. Nos. 5,992,008 and 5,945,231, which
are incorporated by reference herein in their entireties. Generally, the
PEM is made from a polymer, such as Nafion® available from DuPont,
which is a perfluorinated sulfonic acid polymer having a thickness in the
range of about 0.05 mm to about 0.50 mm, or other suitable membranes. The
anode is typically made from a Teflonized carbon paper support with a
thin layer of catalyst, such as platinum-ruthenium, deposited thereon.
The cathode is typically a gas diffusion electrode in which platinum
particles are bonded to one side of the membrane.

[0015]Suitable catalysts for this reaction include platinum and ruthenium,
and other metals. The hydrogen fuel produced from reforming sodium
borohydride is reacted in the fuel cell with an oxidant, such as O2,
to create electricity (or a flow of electrons) and water byproduct.
Sodium borate (NaBO2) byproduct is also produced by the reforming
process. A sodium borohydride fuel cell is discussed in U.S. Pat. No.
4,261,956, which is incorporated by reference herein in its entirety.

[0016]One of the most important features for fuel cell application is fuel
storage. Another important feature is to regulate the transport of fuel
out of the fuel cartridge to the fuel cell. To be commercially useful,
fuel cells such as DMFC or PEM systems should have the capability of
storing sufficient fuel to satisfy the consumers' normal usage. For
example, for mobile or cell phones, for notebook computers, and for
personal digital assistants (PDAs), fuel cells need to power these
devices for at least as long as the current batteries and, preferably,
much longer. Additionally, the fuel cells should have easily replaceable
or refillable fuel tanks to minimize or obviate the need for lengthy
recharges required by today's rechargeable batteries.

[0017]One disadvantage of the known hydrogen gas generators is that once
the reaction starts the gas generator cartridge cannot control the
reaction. Thus, the reaction will continue until the supply of the
reactants run out or the source of the reactant is manually shut down.

[0018]Accordingly, a need exists to obtain a hydrogen gas generator
apparatus that is capable of self-regulating the flow of at least one
reactant into the reaction chamber.

SUMMARY OF THE INVENTION

[0019]An aspect of the invention is directed toward a gas-generating
apparatus, which includes a reaction chamber containing a solid fuel
component and a reservoir containing a liquid fuel component. A fluid
path for introducing the liquid fuel component into the reaction chamber
is provided. The introduction of the liquid fuel component is in response
to a pressure within the reaction chamber.

[0020]Another aspect of the invention is directed toward a gas-generating
apparatus, wherein the flow of liquid reactant to the reaction chamber is
self-regulating.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]These and other features, aspects, and advantages of the present
invention will become better understood when the following detailed
description is read with reference to the accompanying drawings in which
like characters represent like parts throughout the drawings, wherein:

[0022]FIG. 1 is a sectional schematic view of a gas-generating apparatus
according to the present invention;

[0023]FIG. 2 is a sectional schematic view of an alternate embodiment of
the gas-generating apparatus of FIG. 1;

[0024]FIG. 3 is a sectional schematic view of an alternate embodiment of a
gas-generating apparatus according to the present invention;

[0025]FIG. 4 is a sectional schematic view of an alternate embodiment of
the gas-generating apparatus of FIG. 3;

[0026]FIG. 5 is a sectional schematic view of yet another gas-generating
apparatus according to the present invention utilizing a flow pipe
covered by an absorbent roll;

[0027]FIG. 6 is a cross-sectional schematic view of an alternate
embodiment of the absorbent roll of the gas generating apparatus shown in
FIG. 5;

[0028]FIG. 7 is a sectional schematic view of another alternate embodiment
of a gas-generating apparatus according to the present invention having
an inflatable body;

[0029]FIG. 8 is a sectional schematic view of the gas generating apparatus
shown in FIG. 7 where the inflatable body is in an expanded
configuration;

[0030]FIG. 9 is a sectional schematic view of another alternate embodiment
of a gas-generating apparatus according to the present invention having a
solution reservoir and a separate reaction chamber including a screen
element;

[0031]FIG. 10 is a sectional schematic view of the gas generating
apparatus shown in FIG. 9 where the screen element is advanced within the
reaction chamber;

[0032]FIG. 11 is a sectional schematic view of another alternate
embodiment of a gas-generating apparatus according to the present
invention having a manifold with a plurality of flow channels of varying
diameter;

[0033]FIG. 12 is a sectional schematic view of another alternate
embodiment of a gas-generating apparatus according to the present
invention having a manifold with plurality of pressure-tripped valves;

[0034]FIG. 13 is a sectional schematic view of another alternate
embodiment of a gas-generating apparatus according to the present
invention where the liquid fluid component chamber is a spring-loaded
deformable bladder and FIG. 13A is a perspective view of an alternate
fluid conduit; and

[0035]FIG. 14 is a sectional schematic view of another alternate
embodiment of a gas-generating apparatus according to the present
invention having a small-bore pressure-regulating tube connecting a
liquid fuel component reservoir with a solid fuel tablet.

DETAILED DESCRIPTION

[0036]As illustrated in the accompanying drawings and discussed in detail
below, the present invention is directed to a fuel supply, which stores
fuel cell fuels, such as methanol and water, methanol/water mixture,
methanol/water mixtures of varying concentrations, pure methanol, and/or
methyl clathrates described in U.S. Pat. Nos. 5,364,977 and 6,512,005 B2,
which are incorporated by reference herein in their entirety. Methanol
and other alcohols are usable in many types of fuel cells, e.g., DMFC,
enzyme fuel cells and reformat fuel cells, among others. The fuel supply
may contain other types of fuel cell fuels, such as ethanol or alcohols;
metal hydrides, such as sodium borohydrides; other chemicals that can be
reformatted into hydrogen; or other chemicals that may improve the
performance or efficiency of fuel cells. Fuels also include potassium
hydroxide (KOH) electrolyte, which is usable with metal fuel cells or
alkali fuel cells, and can be stored in fuel supplies. For metal fuel
cells, fuel is in the form of fluid borne zinc particles immersed in a
KOH electrolytic reaction solution, and the anodes within the cell
cavities are particulate anodes formed of the zinc particles. KOH
electrolytic solution is disclosed in U.S. Pat. Appl. Pub. No. US
2003/0077493, entitled "Method of Using Fuel Cell System Configured to
Provide Power to One or More Loads," published on Apr. 24, 2003, which is
incorporated by reference herein in its entirety. Fuels can also include
a mixture of methanol, hydrogen peroxide and sulfuric acid, which flows
past a catalyst formed on silicon chips to create a fuel cell reaction.
Moreover, fuels include a blend or mixture of methanol, sodium
borohydride, an electrolyte, and other compounds, such as those described
in U.S. Pat. Nos. 6,554,877, 6,562,497 and 6,758,871, which are
incorporated by reference herein in their entireties. Furthermore, fuels
include those compositions that are partially dissolved in a solvent and
partially suspended in a solvent, described in U.S. Pat. No. 6,773,470
and those compositions that include both liquid fuel and solid fuels,
described in U.S. Pat. Appl. Pub. No. US 2002/0076602. Suitable fuels are
also disclosed in a U.S. provisional application entitled "Fuels for
Hydrogen-Generating Cartridges" filed on Jun. 13, 2005, bearing Ser. no.
60,689,572. These references are also incorporated by reference herein in
their entireties.

[0037]Fuels can also include a metal hydride such as sodium borohydride
(NaBH4) and water, discussed above. Fuels can further include
hydrocarbon fuels, which include, but are not limited to, butane,
kerosene, alcohol, and natural gas, as set forth in U.S. Pat. Appl. Pub.
No. US 2003/0096150, entitled "Liquid Hereto-Interface Fuel Cell Device,"
published on May 22, 2003, which is incorporated by reference herein in
its entirety. Fuels can also include liquid oxidants that react with
fuels. The present invention is therefore not limited to any type of
fuels, electrolytic solutions, oxidant solutions or liquids or solids
contained in the supply or otherwise used by the fuel cell system. The
term "fuel" as used herein includes all fuels that can be reacted in fuel
cells or in the fuel supply, and includes, but is not limited to, all of
the above suitable fuels, electrolytic solutions, oxidant solutions,
gaseous, liquids, solids, and/or chemicals and mixtures thereof.

[0038]As used herein, the term "fuel supply" includes, but is not limited
to, disposable cartridges, refillable/reusable cartridges, containers,
cartridges that reside inside the electronic device, removable
cartridges, cartridges that are outside of the electronic device, fuel
tanks, fuel refilling tanks, other containers that store fuel and the
tubings connected to the fuel tanks and containers. While a cartridge is
described below in conjunction with the exemplary embodiments of the
present invention, it is noted that these embodiments are also applicable
to other fuel supplies and the present invention is not limited to any
particular type of fuel supply.

[0039]The fuel supply of the present invention can also be used to store
fuels that are not used in fuel cells. These applications can include,
but are not limited to, storing hydrocarbons and hydrogen fuels for micro
gas-turbine engine built on silicon chips, discussed in "Here Come the
Microengines," published in The Industrial Physicist (December
2001/January 2002) at pp. 20-25. As used in the present application, the
term "fuel cell" can also include microengines. Other applications can
include storing traditional fuels for internal combustion engines and
hydrocarbons, such as butane for pocket and utility lighters and liquid
propane.

[0041]The gas-generating apparatus of the present invention may include a
reaction chamber, which may include an optional first reactant, and a
reservoir having a second reactant. The first and second reactants can be
a metal hydride, e.g., sodium borohydride, and water. Both reactants can
be in gaseous, liquid, aqueous or solid form. Preferably, the first
reactant stored in the reaction chamber is a solid metal hydride or metal
borohydride, and the second reactant is water optionally mixed with
additives and catalysts. One of the reactants may include methyl
clathrates, which essentially include methanol enclosed or trapped inside
other compounds. Water and metal hydride of the present invention react
to produce hydrogen gas, which can be consumed by a fuel cell to produce
electricity. Other suitable reactants or reagents are discussed below and
are disclosed in the '540 application, previously incorporated above.

[0042]Additionally, the gas-generating apparatus can include a device or
system that is capable of controlling the transport of a second reactant
from the reservoir to the reaction chamber. The operating conditions
inside the reaction chamber and/or the reservoir, preferably a pressure
inside the reaction chamber, are capable of controlling the transport of
the second reactant in the reservoir to the reaction chamber. For
example, the second reactant in the reservoir can be introduced into the
reaction chamber when the pressure inside the reaction chamber is less
than a predetermined value, preferably less than the pressure in the
reservoir, and, more preferably less than the pressure in the reservoir
by a predetermined amount. It is preferable that the flow of the second
reactant from the reservoir into the reaction chamber is self-regulated.
Thus, when the reaction chamber reaches a predetermined pressure,
preferably a predetermined pressure above the pressure in the reservoir,
the flow of the second reactant from the reservoir into the reaction
chamber can be stopped to stop the production of hydrogen gas. Similarly,
when the pressure of the reaction chamber is reduced below the pressure
of the reservoir, preferably below the pressure in the reservoir by a
predetermined amount, the second reactant can flow from the reservoir
into the reaction chamber. The second reactant in the reservoir can be
introduced into the reaction chamber by any known method including, but
not limited to, pumping, osmosis, capillary action, pressure
differential, valve(s), or combinations thereof.

[0043]Referring to FIG. 1, a fuel supply system 10 is shown. System 10
includes a gas-generating apparatus 12 and is configured to be connected
to a fuel cell (not shown) via a fuel conduit 16 and a valve 34.
Preferably, fuel conduit 16 initiates within gas-generating apparatus 12,
and valve 34 is disposed in a sidewall 21b thereof. Fuel conduit 16 is
preferably a flexible tube having a total length that is slightly shorter
than the length of gas-generating apparatus 12.

[0044]Within its sidewalls, gas-generating apparatus 12 preferably
includes three distinct chambers: a fluid fuel component reservoir 44, a
reaction chamber 18, and a void 45, with reaction chamber 18 sealingly
but slidably disposed between reservoir 44 and void 45. Reservoir 44 is
preferably a space formed between a sidewall 21a and a first sidewall 20a
of reaction chamber 18. Reservoir 44 may also, however, include a bladder
or similar fluid container. A fluid fuel component 22, preferably water
and/or an additive/catalyst, resides within reservoir 44. Additional
appropriate fluid fuel components and additives are further discussed
herein. Although fluid fuel component 22 may be pressurized, preferably
it is unpressurized. Void 45 is preferably an empty space on the opposite
side of reaction chamber 18. Suitable additives/catalysts to the fuels or
reactants include, but are not limited to, anti-freezing agents (e.g.,
methanol, ethanol, propanol and other alcohols), catalysts (e.g., cobalt
chloride and other known catalysts), pH adjusting agents (e.g., acids
such as sulfuric acid and other common acids).

[0045]Reaction chamber 18 preferably includes four sidewalls 20a-d made of
a fluid impenetrable material, such as stainless steel or plastic.
Reaction chamber 18 is sealed within the apparatus sidewalls by
deformable members 38, which may be O-rings or gaskets. Reaction chamber
18 is attached to rear apparatus sidewall 21b by a biasing spring 30.
Biasing spring 30, which may be any appropriate spring known in the art,
provides a force that biases reaction chamber 18 toward reservoir 44.
Spring 30 can be replaced by a pressurized gas or liquid, such as butane,
propane or iso-propane, and void 45 may be opened to ambient when spring
30 is used to minimize the build-up of a partial vacuum.

[0046]Disposed within reaction chamber 18 is a solid fuel component 24.
Solid fuel component 24 is preferably a tablet of NaBH4. However,
granules, grains, or other forms of solid material are also appropriate.
Additional appropriate solid fuel components are further discussed
herein. Fillers, additives and other agents and chemicals can be added to
solid fuel NaBH4 to improve its contact with the liquid reactant.

[0047]A connection point 17 for fuel conduit 16 is formed in rear sidewall
20c of reaction chamber 18. Connection point 17 may simply be a hole
through rear sidewall 20c, preferably located at or near the top thereof.
In such a case, fuel conduit 16 is preferably fixedly attached to or
within connection point 17, such as with an adhesive. However, connection
point 17 may also include a nozzle onto which fuel conduit 16 may be
press fit and then optionally fixed with an adhesive or similar material.
Also, optionally, a gas-permeable, liquid impermeable membrane 32 may be
affixed over the reaction chamber-facing side of connection point 17.
Membrane 32 prevents liquids or byproducts from being transferred to the
fuel cell via fuel conduit 16. Fillers or foam can be used in combination
with membrane 32 to retain liquids or byproducts and to reduce clogging.
Membrane 32 may be formed from any liquid impermeable, gas permeable
material known to one skilled in the art. Such materials can include, but
are not limited to, hydrophobic materials having an alkane group. More
specific examples include, but are not limited to: polyethylene
compositions, polytetrafluoroethylene, polypropylene, polyglactin
(VICRY®), lyophilized dura mater, or combinations thereof. Gas
permeable member 30 may also comprise a gas permeable/liquid impermeable
membrane covering a porous member. Examples of such membrane are
CELGARD® and GORE-TEX®. Other gas permeable, liquid impermeable
members usable in the present invention include, but are not limited to,
SURBENT® Polyvinylidene Fluoride (PVDF) having a porous size of from
about 0.1 μm to about 0.45 μm, available from Millipore
Corporation. The pore size of SURBENT® PVDF regulates the amount of
water exiting the system. Materials such as electronic vent type material
having 0.2 μm hydro, available from W. L. Gore & Associates, Inc., may
also be used in the present invention. Additionally, 0.25 inch diameter
rods having a pore size of about 10 μm or 2 inch diameter discs with a
thickness of about 0.3 μm available from GenPore, and sintered and/or
ceramic porous material having a pore size of less than about 10 μm
available from Applied Porous Technologies Inc. are also usable in the
present invention. Furthermore, nanograss materials, from Bell Labs, are
also usable to filter the liquid. Nanograss controls the behavior of tiny
liquid droplets by applying electrical charges to specially engineered
silicon surfaces that resemble blades of grass. Additionally, or
alternatively, the gas permeable, liquid impermeable materials disclosed
in commonly owned, co-pending U.S. patent application Ser. No. 10/356,793
are also usable in the present invention, all of which are incorporated
by reference herein in their entireties. Such a membrane 32 may be used
in any of the embodiments discussed herein.

[0048]A fluid introduction valve 26 is disposed in an opposite reaction
chamber sidewall 20a. Fluid introduction valve 26, which is preferably a
check valve, controls the communication of fluid fuel component 22 from
reservoir 44 into reaction chamber 18. Valve 26 may be any
pressure-opened, one-way valve known in the art, such as a check valve or
a valve having a pressure responsive diaphragm, which opens when a
threshold pressure is reached. Within reaction chamber 18, valve 26
preferably includes a nozzle 28 to disperse the fluid fuel component 22
within reaction chamber 18. As will be recognized by those in the art,
valve 26 may be optionally omitted, as shown in FIG. 2. In that
embodiment, which is the same in all other respects to the embodiment
shown in FIG. 1, a small diameter hole 28a acts as the pressure-triggered
nozzle for dispersing fluid fuel component 22 into reaction chamber 18.
Hole 28a is preferably located at the bottom of chamber 18 to minimize
the migration of gas into reservoir 44. Alternatively, solid fuel
component 24 can be positioned adjacent to hole 28a to minimize the
migration of gas into reservoir 44.

[0049]When hydrogen gas is needed by the fuel cell, on/off or shut-off
valve 36, as shown in FIG. 1, is opened. On/off valve 36 can be any valve
known in the art, including but not limited to, solenoid valve, check
valve, etc., and can be opened manually by the user or by the controller
controlling the fuel cell. To generate gas to be used as fuel for the
fuel cell, fluid fuel component 22 is transferred into reaction chamber
18 to react with solid fuel component 24. Gas-generating apparatus 12
does this automatically. Spring 30 pushes reaction chamber 18 toward
reservoir 44 with a constant force F. Force F, combined with the
hydrostatic pressure HP within reservoir 44, create a total reservoir
pressure P22 on the reservoir 44 side of valve 26. While on/off
valve 36 is opened, the reaction chamber pressure P18 within
reaction chamber 18 is dynamically cycled from high to low as gas is
created and then transferred through fuel conduit 16. When total
reservoir pressure P22 is greater than reaction chamber pressure
P18, valve 26 opens and fluid fuel component 22 flows into reaction
chamber 18, which moves toward sidewall 21a. When the difference between
total reservoir pressure P22 and reaction chamber pressure P18
falls below the triggering point for valve 26, valve 26 closes and
reaction chamber 18 stops moving while gas accumulates therewithin. When
reaction chamber pressure P18 reaches a triggering pressure TP, fuel
valve 34 opens, and fuel gas begins to flow out of reaction chamber 18.
When sufficient fuel gas has been transferred out of reaction chamber 18,
fluid valve 26 opens and additional fluid fuel component 22 enters
reaction chamber 18 while gas is still being transferred out of reaction
chamber 18 through fuel conduit 16. Eventually, reaction chamber pressure
P18 falls below triggering pressure TP to hold open fuel transfer
valve 34. This allows fuel gas to accumulate within reaction chamber 18
to eventually close fluid transfer valve 26. This cycle is summarized
below in Table 1.

[0050]FIG. 3 shows another embodiment of a fuel supply 210 including a
gas-generating apparatus 212 where a fluid fuel component 222, similar to
fluid fuel component 22 discussed above, is held in a reservoir 244 and
transferred to a reaction chamber 218 containing a solid fuel component
224, similar to solid fuel component 24 discussed above. In this
embodiment, reaction chamber 218 is formed from three sidewalls 220a-c. A
bottom of reaction chamber 218 is sealed by a solid fuel carrier 225,
which fits snugly and slidably between sidewalls 220b, 220c. Solid fuel
carrier 225 is sealed in the opening by deformable members 238, which may
be O-rings, gaskets or the like. Alternatively, solid fuel carrier 225
may itself be formed from an appropriately sealing deformable material,
although carrier 225 is preferably made from a rigid material such as
stainless steel or plastic. Carrier 225 includes an open container
portion filled with solid fuel component 224, such as a tablet or
granules of sodium borohydride.

[0051]Carrier 225 is biased into reaction chamber 218 by a biasing spring
230, which may be any type of spring known in the art. Biasing spring 230
is fixedly mounted onto a base 231, such as a sidewall of fuel supply
210, fuel cell, or other similar platform, and biasing spring 230
provides a constant force on carrier 225.

[0052]Fixedly attached to a bottom of carrier 225 is a crank arm 242.
Crank arm 242 extends from the bottom of carrier 225, through a sealed
opening in reservoir 244, and terminates as a stopper 240 positioned over
or a fluid transfer hole 226 formed at the interface of reservoir 244 and
reaction chamber 218. While crank arm 242 may be made of any rigid
material that will not react with fluid fuel component 222, stopper 240
preferably includes an exterior coating of a deformable material, such as
rubber or silicone, capable of sealing hole 226.

[0053]Through top sidewall 220a, fluid transfer hole 226 connects fluid
fuel component reservoir 244 with reaction chamber 218. Similar to the
embodiment discussed above with respect to FIG. 1, the end of fluid
transfer hole 226 facing into reaction chamber 218 preferably forms a
nozzle 228 so that any fluid fuel component passing through fluid
transfer hole 226 is dispersed within reaction chamber 218. Also disposed
in top sidewall 220a is a fuel transfer valve 234 that connects reaction
chamber to a fuel conduit 216. Similar to valve 34 discussed above, fuel
transfer valve 234 is preferably a pressure-triggered valve such as a
check valve, and is optionally covered by a gas-permeable, liquid
impermeable membrane 232, which may be any such membrane known in the
art.

[0054]Similar to the embodiment discussed above with respect to FIG. 1,
the operation of gas-generating apparatus 212 is preferably automatically
controlled or cycled by the balance between the pressures and forces
within apparatus 212. The reaction chamber pressure P218 changes
dynamically due to the production of fuel gas within reaction chamber 218
and the transfer of that fuel gas to a fuel cell (not shown) through fuel
transfer valve 234. Spring 230 provides a constant F upward on carrier
225. When the force from P218 is greater than F, carrier 225 is
pushed downward, thereby moving crank arm 242 downward as well.
Eventually, carrier 225 will move far enough due to the high P218 to
push stopper 240 into place, thereby shutting off the flow of fluid fuel
component into reaction chamber 218. Fuel transfer valve 234 is opened
only when P218 is greater than a triggering pressure TP.

[0055]Preferably, reaction chamber 218 is charged with fuel or inert gas
so that the initial state of carrier 225 is in a downward position and
spring 30 is compressed. Alternately, the user may manually unseal
stopper 240 by known mechanical means (e.g., pull tabs, slides, etc.), or
stopper 240 is automatically removed when attached to the fuel cell, so
that no initial pressure is necessary.

[0056]In an embodiment, fluid fuel component 222 is stored in a bladder
(not shown) and reservoir 244 is pressurized by compressed gas, liquefied
gas, compressed foam or loaded spring, so that fluid component 222 can
exit reservoir 244 when reservoir 244 is positioned in any orientation.

[0057]Also, preferably, P218 is higher than the TP for valve 234.
When connected to a fuel cell, gas is transferred out of reaction chamber
218, thereby reducing P218. Eventually, sufficient gas is
transferred such that F from spring 230 overcomes the force from
P218 and pushes carrier 225 upward, thereby unplugging stopper 240
from fluid transfer hole 226 via crank arm 242. Fluid 222 is then sprayed
into reaction chamber 218 through nozzle 228. However, gas continues to
be transferred out of reaction chamber 218 through valve 234 until
P218 falls below the TP. When the valve closes, the pressure in
reaction chamber 218 again builds until the force from P218
overcomes F from spring 230, and stopper 240 again plugs fluid transfer
hole 226. This cycle is summarized in Table 2.

[0058]Another device to control the pressure of reaction chamber 218 is to
place a secondary fuel cell 214' on a sidewall 220b, as shown in FIG. 3.
Secondary fuel cell 214' consumes excess hydrogen to minimize pressure
P218 when shut-off valve 236 is closed. As shown, secondary fuel
cell 214' is positioned on sidewall 220b with the anode side 211 facing
the reaction chamber 218 and in contact with the hydrogen gas therein and
with the cathode side 209 facing the ambient air and in contact with
oxygen. Preferably, a movable cover gate 213 is provided to cover the
cathode side when the gas-generating apparatus is in operation to prevent
air from reaching fuel cell 214' so that hydrogen is not wasted in
consumption by secondary fuel cell 214' when desired by the main fuel
cell (not shown). When the user or controller opens valve 236, gate 213
is moved to cover secondary fuel cell 214'. When the user or controller
closes valve 236 (or when pressure P218 exceeds a threshold level)
gate 213 is moved to allow air to contact the cathode side to consume
excess hydrogen. An electrical-energy consuming device, such as a
resistor 215, light emitting diode, or similar electricity consuming
and/or dissipating circuit, is provided as shown schematically to consume
the electricity produced by fuel cell 214'. Secondary fuel cell 214' and
cover 213 can be used with any of the embodiments of the present
invention.

[0059]FIG. 4 shows a similar gas-generating apparatus 212 to the one shown
and discussed above with respect to FIG. 3. In this embodiment, however,
instead of a crank arm connected directly to a bottom of carrier 225, a
shaft 247 is hingedly attached to the bottom of carrier 225 and to a
crank wheel 246. A biasing spring 230 is fixedly attached to crank wheel
246 on one end and to a solid base 231 on the other. Biasing spring 230
provides a constant force F that tends to push crank wheel 246 in a
clockwise direction.

[0060]A crank arm 242 is fixedly attached to crank wheel 246 at a lower
end of crank wheel 246. An upper end of crank arm 242 is hingedly
attached to a tube 241 at an attachment point 239 containing a slidable
stopper 240. The other end of tube 241 is hingedly attached to an access
point 237 above fluid transfer hole 226. Stopper 240 may be any material
or shape, as long as stopper 240 can move easily within tube 241 and plug
hole 226.

[0062]As with the embodiment shown in FIG. 3, this process is preferably
controlled automatically by the pressure and force balances within
gas-generating apparatus 212. For example, reaction chamber 218 is
preferably initially charged such that the force due to P218 within
reaction chamber 218 pushes downward on to carrier 225, far enough that
crank arm 242 tilts tube 241 to such an extent that stopper 240 slides
toward access point 237 and plugs hole 226. Also, P218 is above TP,
so valve 234 opens when connected to the fuel cell and fuel gas flows out
of reaction chamber 218. At this point, gas generation within reaction
chamber 218 slows and eventually stops causing P218 to decrease.
P218 eventually decreases to a point where the force from P218
is no longer sufficient to overcome F, which causes crank wheel 246 to
turn clockwise. This motion tilts tube 241 via crank arm 242 so that
stopper 240 slides toward attachment point 239, thereby unplugging fluid
transfer hole 226, which allows fluid fuel component 222 to flow into
reaction chamber 218 through nozzle 228. Gas is again generated within
reaction chamber 218. Gas is removed from reaction chamber 218 through
valve 234 at a rate that is preferably slower than the rate at which gas
continues to be generated within reaction chamber 218, so that P218
continues to build. If P218 falls below TP, valve 234 closes, which
allows gas to accumulate within reaction chamber 218. This pressure and
force cycle is summarized in Table 3.

[0063]FIG. 5 shows yet another gas-generating apparatus 312 having a
reaction chamber 318 defined by sidewalls 320, similar to those described
above with respect to FIGS. 1-4. A fuel transfer valve 334, such as a
check valve, traverses one of the sidewalls 320 to allow fuel gas formed
within reaction chamber 318 to pass therethrough and into a fuel conduit
316, similar to the fuel conduit described above with respect to FIGS. 3
and 4.

[0064]A fluid transfer tube 350 enters reaction chamber 318 through a
sidewall, preferably an upper sidewall. Fluid transfer tube is attached
at one end to a reservoir that holds a fluid fuel component (not shown).
The fluid fuel component is preferably similar to the fluid fuel
components described above.

[0065]Fluid transfer tube 350 extends into reaction chamber 318. Toward
the free end of fluid transfer tube 350 several flow channel holes 352
are formed along the length of fluid transfer tube 350. Fluid fuel
component is transferred through fluid transfer tube 350 so that the
fluid fuel component can flow out of flow channel holes 352.

[0066]Covering flow channel holes 352 is a covering formed of a solid fuel
component 324 and a material 354 that quickly absorbs the fluid fuel
component and pulls it through solid fuel component 324. Preferably,
solid fuel component 324 is in granular form so that the fluid fuel
component can be readily passed therethrough. Preferably, material 354 is
capable of absorbing liquid, but which allows gas to pass through the
material. One example of such a material is paper fluff containing sodium
polyacrylate crystals; such a material is commonly used in diapers. Other
examples include, but are not limited to, fillers and foams.

[0067]In one embodiment, shown in FIG. 6, several-layers of solid fuel
component 324a, 324b and material 354a, 354b are wound around fluid
transfer tube 350. However, as few as one layer may be used. As the fluid
fuel component is pulled through the solid fuel component, fuel gas is
formed and passes through material 354 and into reaction chamber 318.
Further, fluid may contact a filler or foam first, and then be
transferred to the solid fuel through capillary action.

[0068]Sodium polyacrylate crystals form a gel with water and the water gel
can react with a metal hydride, as shown in commonly owned, co-pending
United States patent application entitled "Fuel Compositions for Fuel
Cells and Gas-Generators Utilizing Same" bearing Ser. No. 60/782,632, and
filed on Mar. 15, 2006. The '632 application is incorporated herein by
reference in its entirety.

[0069]A fluid control valve 326 is preferably disposed within fluid
transfer tube 350 to control the flow of the fluid fuel component through
to flow channels 352. Fluid control valve 326 is preferably a
pressure-triggered valve that is opened and closed in response to
pressure P318 in reaction chamber 318. A pressure transfer tube 356
allows for the exposure of a small portion of the fuel gas formed within
reaction chamber 318 to fluid control valve. When P318 is higher
than the triggering pressure for fluid control valve 326, fluid control
valve 326 closes and shuts off the flow of fluid fuel component through
fluid transfer tube 350. When the P318 falls below the triggering
pressure for fluid control valve 326, fluid control valve 326 opens and
allows more fluid fuel component into fluid transfer tube 350.

[0070]Similarly, the operation of fuel transfer valve 334 is also
controlled by P318. When P318 is higher than a triggering
pressure TP for fuel transfer valve 334, then fuel transfer valve 334
opens to allow fuel gas to flow through fuel conduit 316 and into the
fuel cell. When P318 falls below the triggering pressure for fuel
transfer valve 334, then fuel transfer valve 334 closes, which allows gas
pressure to build within reaction chamber. As with the embodiments
discussed above, reaction chamber is preferably charged upon manufacture
so that the production of gas can be initiated.

[0071]FIGS. 7 and 8 show yet another embodiment of a gas-generating
apparatus 412 of a fuel supply 410 is shown. In this embodiment a
reaction chamber 418 is defined by an expandable bladder 458. Expandable
bladder 458 may be made of any type of material capable of expanding and
contracting without the application of external forces. For example,
expandable bladder 458 may be a balloon-like structure made of rubber or
latex. Alternatively, expandable bladder 458 may be made from a plastic
material that may be heat set to return to its original configuration
when emptied, such as PET.

[0072]Expandable bladder 458 is preferably suspended near the center of
gas-generating apparatus 412 on a support 460. Expandable bladder 458
also sealingly surrounds a cage 462 filled with a solid fuel component
such as sodium borohydride that extends from support 460. Preferably, the
solid fuel component is granular, although a solid tablet or slug may
also be used. Cage 462 may be made of any material inert to the solid
fuel component and a liquid fuel component 422 that is also disposed
within expandable bladder 458. For example, cage 462 may be made of
stainless steel or plastic. Holes 464 are formed in cage 462 so that
liquid fuel component 422 can come into contact with the solid fuel
component. Liquid fuel component 422 is similar to the liquid fuel
components discussed in the above embodiments.

[0073]A second end of expandable bladder 458 is attached to a fuel conduit
416, which is configured to transfer fuel gas formed within reaction
chamber 418 to a fuel cell. Fuel conduit 416 is similar to those fuel
conduits discussed above with respect to the embodiments shown in FIGS.
3-6. A fuel transfer valve 434, preferably a pressure triggered valve
such as a check valve, is configured to control the outflow of fuel gas
from reaction chamber 418.

[0074]In operation, expandable bladder 458 is initially in a collapsed
configuration, such as is shown in FIG. 7. When collapsed, liquid fuel
component 422 is in contact with cage 462. As such, liquid fuel component
422 can flow through holes 464 to react with the solid fuel component.
Fuel gas such as hydrogen is produced. As fuel gas accumulates within
reaction chamber 418, expandable bladder 458 expands. When the RCP within
reaction chamber 418 exceeds a triggering pressure TP for fuel transfer
valve 434, fuel transfer valve 434 opens to allow the transfer of fuel
gas from reaction chamber 418 to the fuel cell. When expandable bladder
458 reaches a critical size, such as is shown in FIG. 8, all of liquid
fuel component 422 collects in the bottom of expandable bladder 458 and
is no longer in contact with the solid fuel component within cage 462. As
such, additional reaction between liquid fuel component 422 and solid
fuel component cannot occur until enough gas has been transferred out of
reaction chamber 418 to the fuel cell. An optional one-way relief valve
430 may be included to prevent over pressurization of expandable bladder
458, such as by venting the fuel gas to the atmosphere. As will be
recognized by those in the art, gas-generating apparatus 412 works in any
orientation.

[0075]FIGS. 9 and 10 show yet another embodiment of a gas-generating
apparatus 512 of a fuel supply 510 adapted to be connected to a fuel cell
(not shown) via a fuel conduit 516. Gas-generating apparatus 512 includes
two chambers formed within sidewalls 520, a pressurized liquid fuel
component chamber 544 and a reaction chamber 518. Sidewalls 520 are
preferably formed of a material inert to a liquid fuel component 522,
such as water or water with additives, contained within pressurized
liquid fuel component chamber 544 and a solid fuel component 524, such as
sodium borohydride, contained within reaction chamber 518. A fluid
transfer conduit 588 connects pressurized liquid fuel component chamber
544 and reaction chamber 518. As with the embodiments discussed above, a
fuel transfer valve 534, preferably a pressure-triggered valve such as a
check valve, and an on/off valve 36 (not shown) downstream of valve 534
allow for the transfer of fuel from reaction chamber 518 to fuel conduit
516 and on to a fuel cell.

[0076]A spring-biased piston 584 is sealingly and slidingly disposed,
initially, at or near the top of pressurized liquid fuel component
chamber 544. Preferably, piston 584 is sealed with a lubricating sealing
material 586, such as petroleum jelly, although other sealing components
such as O-rings or gaskets may be used. A biasing spring 530 provides a
continuous force F on piston 584 so that liquid fuel component 522 is
constantly being forced toward reaction chamber 518. Similar to the
discussion above, spring 530 can be replaced by a pressurized material,
such as liquid/gaseous hydrocarbon, e.g., butane, propane or iso-propane.

[0077]A flexible fluid tube 582 is fluidly connected to fluid transfer
conduit 588, discussed below, and terminates in a nozzle or opening 528
within reaction chamber 518. Fluid fuel component 522 selectively passes
through flexible fluid tube 582 into reaction chamber 518. Flexible fluid
tube 582 passes through or is in contact with a mesh piston 580. Mesh
piston 580 is biased toward fuel component 524 by a biasing spring 572.
Biasing spring 572 provides a continuous force on mesh piston 580 to bias
it into fuel component 524 toward fuel conduit 516. Mesh piston 580 is
kept in contact with solid fuel component 524, which is preferably formed
of granules that are too large to pass through the mesh of piston 580, by
spring 572. However, as fluid fuel component 522 flows into reaction
chamber 518 through nozzle 528 and reacts with solid fuel 524, as shown
in FIG. 10 both fuel gas and a slurry 590, e.g., aqueous borate, are
formed. Slurry 590 can flow through the mesh of piston 580 to accumulate
underneath mesh piston 580. Spring 572 then continually pushes mesh
piston 580 into the un-reacted portion solid fuel component 524. As such,
the fluid fuel component flowing out of nozzle 528 is continually in
contact with fresh solid fuel component 524 that is relatively free from
the byproducts.

[0078]Similar to the embodiments discussed above, gas generating apparatus
512 is also self-regulated. Diaphragm 574, an optional spring 573, and
valve 526, positioned below mesh piston 580, are exposed to the pressure
P518 within reaction chamber 518. A fluid conduit 575 is formed
through diaphragm 574 and fluidly connects fluid conduit 588 to flexible
tube 582. As pressure builds within reaction chamber 518, a triggering
pressure, TP, of diaphragm 574 is eventually reached. When the triggering
pressure of diaphragm 574 is reached, diaphragm 514 deforms to close
valve 526 (not shown), thereby cutting off the flow of fluid fuel
component into reaction chamber 518. Fuel gas flows out of fuel transfer
valve 534 until the P518 decreases to below TP, where diaphragm 574
opens again to once again initiate the production of fuel gas by
introducing additional liquid fuel component 522 into reaction chamber
518. Spring 573 assists diaphragm 574 in returning to the open position.
Valve 526 can be any valve that can open and close as diaphragm 574
reacts to P518, e.g., check valve.

[0079]FIG. 11 shows yet another embodiment of a gas-generating apparatus
612 adapted to be connected to a fuel cell (not shown) via a fuel conduit
616. In this embodiment, a reaction chamber 618 contains a quantity of a
solid fuel component 624, which is preferably in granular or powdered
form. Reaction chamber 618 includes two opposing sidewalls 620, which are
made of a solid, non-reactive material similar to sidewalls 20 as
discussed above. However, a bottom 680 of reaction chamber 618 is
preferably made of a porous non-reactive material, such as a mesh or a
sheet of material with holes disposed therethrough. Fiberglass is one of
many materials appropriate for use as bottom 680. The pores of bottom 680
are dimensioned such that the individual grains of solid fuel component
624 cannot pass therethrough.

[0080]A top 632 of reaction chamber 618 is preferably formed of a
gas-permeable, liquid impermeable membrane, such as membrane 32 as
described above with respect to FIG. 1. Examples of an appropriate
membrane include CELGARD® and GORE-TEX®. A fuel gas reservoir 619
is positioned adjacent to top membrane 632 to receive therethrough the
fuel gas produced within reaction chamber 618. A valve 634, such as a
check valve, controls the outflow of fuel gas from fuel gas reservoir 619
to fuel conduit 616. Valve 634 may be any type of valve known in the art
and is similar in design and function to valve 34 as described above with
respect FIG. 1.

[0081]A manifold 679 is positioned adjacent to bottom 680. Preferably,
several flow channels 652a-f are formed in manifold 679. As will be
recognized by those in the art, the number of flow channels will vary
widely depending on factors including the type of fuel, the type of fuel
cell, and the device being driven by the fuel cell. Preferably, the
number of flow channels ranges from 2 to about 100, and more preferably,
from about 50 to about 75.

[0082]Flow channels 652a-f are fluidly connected to a feeder tube 650
through which a fluid fuel component (not shown) is provided from a
reservoir (not shown). The initial flow of fluid through feeder tube 650
is preferably controlled by a controller (not shown) which signals a need
for additional fuel and opens a valve (not shown) disposed between the
fluid reservoir and feeder tube 650. Alternatively, a user may initiate
flow by triggering a switch to open such a valve. Manifold 679 is
configured to allow only one flow channel 652 a-f to receive the fluid
fuel component from feeder tube 650 at any given time so that different
areas of the solid fuel component 624 are reacted successively. In other
words, if the fluid fuel component is flowing through flow channel 652a,
flow channels 652b-f contain no fluid fuel component so that the solid
fuel component 624 disposed above the unused flow channels 652 b-f
remains dry and unreacted.

[0083]This series use of flow channels 652a-f is preferably achieved in
part by providing each flow channel with a diameter that is different
from the other flow channels. Preferably, flow channel 652a has the
largest diameter, with each successive flow channel having a slightly
smaller diameter progressing in the direction of flow. In other words,
the diameter of flow channel 652b is greater than the diameter of flow
channel 652c, and so on. As in known in the art, fluid flows in the path
of least resistance. As the narrower diameter of the next flow channel
downstream is essentially constricting the flow of the fluid, the fluid
tends to follow the path through the largest available channel. For
example, if presented with a flow path through flow channel 652a or flow
channel 652b, most of the fluid will flow through flow channel 652a.

[0084]This tendency of the fluid to flow through the largest available
channel is optionally enhanced by configuring feeder tube 650 with a
stepwise construction, where the diameter of feeder tube 650 increases
slightly just prior to reaching the next successive flow channel 652. For
example, as feeder tube 650 is relatively narrow in the vicinity of
relatively wide flow channel 652a, the fluid in feeder tube 650 will tend
to enter flow channel 652a instead of continuing to flow along feeder
tube 650.

[0085]As the fluid fuel component flows into reaction chamber 618 through
flow channel 652a, the fluid fuel component reacts with solid fuel 624.
For example, if the solid fuel component 624 is sodium borohydride and
the fluid fuel component is water or doped water, then hydrogen gas and a
slurry of aqueous borate is produced. If the slurry is not removed from
the mouth of flow channel 652a, the slurry tends to harden like concrete.
This hardened slurry eventually entirely clogs flow channel 652a. As flow
channel 652a is now blocked, the fluid in feeder tube 650 will flow to
the next available path, flow channel 652b. While some of the fluid may
flow past flow channel 652b, it is believed that this flow amount is
insufficient to flow into any of the remaining flow channels 652c-f until
flow channel 652b is also clogged with hardened slurry. This process
continues until all flow channels 652a-f are clogged and/or all of solid
fuel component 624 is consumed.

[0086]Optionally, a second mesh 681 is disposed at the inlet of each of
flow channels 652a-f. Second mesh 681 has a very small pore size so that
fluid can flow therethrough but any slurry that might escape reaction
chamber 618 is captured so as not to contaminate the fluid fuel component
or clog feeder tube 650. As will be recognized by those in the art, other
hydraulic parameters of flow channels 652 may also be changed to
manipulate the tendency of fluid to choose a particular flow path, such
as the height of the flow channels, where each successive downstream
channel is taller than the previous flow channel. Any combination of
hydraulic parameters may be used.

[0087]Referring to FIG. 12, another configuration for a gas-generating
apparatus 712 that allows access to successive flow channels 752a-f is
shown. In this embodiment, which is similar to the embodiment shown in
FIG. 11, access to downstream flow channels 752b-f is controlled by a
series of valves 753a-e. Valves 753a-e are preferably pressure-triggered
valves such as check valves or diaphragm valves. As fluid flows through a
feeder tube 750, all valves 753a-e are closed so that the fluid must flow
into flow channel 752a. As described above, flow channel 752a will clog
with hardened slurry. When flow channel 752a is blocked, the pressure of
the fluid in feeder tube 750 will increase until the first valve 753a is
opened. The fluid may now flow into flow channel 752b. Preferably, once
valve 753a is opened, it will not close again, such as by having an
internal frangible member, as the flow pressure typically decreases once
the new flow path is opened. As will be recognized by those in the art,
each valve 753a-e may optionally be replaced with a frangible membrane.
This process of clogging flow channels 752a-f and opening valves or
breaking frangible membranes continues until all flow channels 752a-f are
clogged and/or all solid fuel component 724 is spent.

[0088]Referring to FIG. 13, yet another gas-generating apparatus 812 is
shown. Similar to previous embodiments, a reaction chamber 818 is
contained within a housing 820. Housing 820 may be made of any material
capable of containing a gas-generating reaction, preferably a material
inert to the reaction, such as plastic or stainless steel. One end of
housing 820 is sealed with a stopper 840. Stopper 840 is made of any
material capable of sealing housing 820 against the escape of gas
produced during reaction or liquid fuel component 822. The opposite end
of housing 820 includes a valve 834, leading to the fuel cell (not shown)
or a conduit leading to the fuel cell (not shown). Valve 834 is similar
to other valves discussed herein and is preferably a check valve or a
shut-off valve.

[0089]A solid fuel component 824 such as sodium borohydride lines the
sidewalls of housing 820. Preferably, solid fuel component 824 is in
powder or granular form, although solid fuel component 824 may be in
tablet form. If solid fuel component 824 is provided in powder or
granular form, a screen or mesh 827 is disposed over solid fuel component
824. The pore size of mesh 827 is sufficiently small to allow the liquid
fuel component 822 access to solid fuel component 824 while retaining
solid fuel component 824. Also, solid fuel component 824 may be divided
into several compartments by dividers 825. Dividers 825 are made of a
material capable of sealing each compartment so that liquid fuel
component 822 cannot migrate from one divider to the next. Optionally,
the granules of solid fuel component 824 may be encased in a time-release
material, where different time-release materials are used, such as
water-soluble materials of varying thicknesses. As such, some of the
solid fuel component 824 may be used quickly, while the remaining solid
fuel component 824 is reserved for use at a later point in time.

[0090]Liquid fuel component 822 is preferably water or a water-based gel,
similar to the liquid fuel components discussed above. The water-based
gel may be formed by mixing water with a hydrophilic compound, such as
sodium polyacrylate crystals. Water gel is discussed above and disclosed
in the '632 patent application, previously incorporated by reference.
Liquid fuel component 822 is contained within a bladder 844. Bladder 844
is made of a deformable material which is substantially inert to liquid
fuel component 822, such as rubber, silicone or thin-walled plastic.
Preferably, bladder 844 is configured with a plurality of corrugations to
allow bladder 844 to collapse more easily and in a controlled manner.

[0091]Fluidly connected to bladder 844 is a fluid conduit 882 that
terminates in a nozzle 828. Fluid conduit 882 and nozzle 828 provide a
fluid path to direct liquid fuel component 822 to a particular section of
solid fuel component 824, such as a single compartment. Preferably, fluid
conduit 882 and nozzle 828 are relatively small bore components, so that
only a small quantity of liquid fuel component 822 may be dispensed at
any given point in time. As shown in FIG. 13A, while nozzle 828 is shown
as a single point nozzle in FIG. 13, nozzle 828' connected to fluid
conduit 882' may include multiple outlets, such as, for example, a hollow
ring fluidly connected to bladder 844 having multiple holes formed
therein that serve as multiple and simultaneous fluid outlets.

[0092]A spring 830 is disposed on the end of bladder 844 opposite to fluid
conduit 882 and nozzle 828. Spring 830 is preferably a constant force
spring. Spring 830 may be any type of spring capable of providing a
constant pulling force, such as a flat or clock spring. Preferably,
spring 830 is made of a material substantially inert to liquid fuel
component 822, such as plastic or stainless steel. One end of spring 830
extends through one end of bladder 844 to be fixedly attached to the
opposite end of bladder 844 at or near fluid conduit 882. As such, spring
830 pulls the nozzle end of bladder 844 toward stopper 840. The pulling
of spring 830 squeezes bladder 844, thereby forcing liquid fuel component
822 through fluid conduit 882 and out nozzle 828 to be introduced to
solid fuel component 824. Gas is produced within reaction chamber 818.
When the pressure within reaction chamber 818 reaches a threshold value,
valve 834 opens to allow the gas to be transferred to the fuel cell.
Alternatively, valve 834 is a shut-off valve and can be opened by a user
or a controller. As bladder 844 empties, nozzle 828 moves toward stopper
840 as discussed further below, thus ensuring that liquid fuel component
822 is introduced to a new section of solid fuel component 824.

[0093]As spring 830 pulls on bladder 844, gas is continuously be produced
by the introduction of liquid fuel component 822 to solid fuel component
824. However, it may not be desirable to produce gas without cessation.
For example, when shut-off valve such as valve 834 is closed, the
production of hydrogen should stop. Such a valve may be manually
triggered, such as by the user or via a controller which monitors the
usage of fuel by the fuel cell. When such a shut-off valve is closed, gas
cannot be transferred out of housing 820 to the fuel cell. As such,
pressure from the produced gas will build within reaction chamber 818 or
housing 820. While the pressure may be relieved with, for example, a
pressure relief check valve (not shown) or a secondary fuel cell, as
discussed above, disposed in the sidewalls of housing 820, the production
of gas should stop after closing a shut-off valve.

[0094]As such, gas-generating apparatus 812 is preferably provided with a
pressure-sensitive sleeve 832 configured to stop the winding of spring
830. Pressure-sensitive sleeve 832 is provided adjacent stopper 840 and
is adjacent to at least a portion of spring 830. Pressure-sensitive
sleeve 832 is preferably made of a rigid material readily translated by
the pressure within housing 820, such as plastic, resin, metal or the
like. Pressure-sensitive sleeve 832 is slidably disposed within housing
820 spaced apart from stopper 840 to created a gap 831 so that
pressure-sensitive sleeve 832 is free to translate within housing 820
into and out of gap 831. Pressure-sensitive sleeve 832 is biased away
from stopper 840 by a spring 829, which may be any type of spring known
in the art, such as a coiled compression spring or a gas or liquid
hydrocarbon.

[0095]Once the pressure within reaction chamber 818 reaches a threshold
level, the force provided by spring 829 biasing pressure-sensitive sleeve
832 away from stopper 840 is overcome so that pressure-sensitive sleeve
832 translates toward stopper 840. In so doing, pressure-sensitive sleeve
832 squeezes spring 830, thereby preventing spring 830 from winding
further. As such, spring 830 can no longer pull on bladder 844 and no
additional liquid fuel component is expelled from bladder 844. When gas
is once again released from housing 820 to lower the pressure therewithin
below the threshold level, spring 829 expands and pressure-sensitive
sleeve 832 is translated back to its original position, thereby releasing
spring 830. Spring 830 once again may pull on the nozzle end of bladder
844, and additional gas may be produced.

[0096]Yet another gas-generating apparatus 912 is shown in FIG. 14.
Gas-generating apparatus 912 includes a housing 920 similar to the
housings for the other gas-generating apparatus shown and discussed
above. Housing 920 is generally configured to define a reaction chamber
918 containing a solid fuel component 924, such as sodium borohydride,
and a liquid fuel component chamber 944 containing a liquid fuel
component 922, such as water. As will be recognized by those in the art,
any of the solid or liquid fuel components discussed in this application
are appropriate for use with this embodiment.

[0097]A piston 980 slidably disposed within housing 920 divides the
interior of housing 920 into liquid fuel component chamber 944 and
reaction chamber 918. Piston 980 is sealingly disposed within housing
920. As such, piston 980 is preferably made from a deformable material
which is non-reactive with either liquid fuel component 922, solid fuel
component 924 or the gas produced by the reaction therebetween, and is
covered with a gel-like material which enhances the sealing aspects of
piston 980 and eases the sliding motion thereof, such as petroleum jelly.
Alternatively, as shown in FIG. 14, piston 980 may be made from any rigid
material which is similarly non-reactive as the deformable material
discussed above, but includes at least one sealing element 938, such as a
rubber or silicone O-ring or a gel-like lubricating material such as
petroleum jelly. A sprag 981 or similar structure is provided adjacent
piston 980 within reaction chamber 918 so that piston 980 is slidable
only toward liquid fuel component chamber 944. Sprag 981 is preferably a
plastic or metal concave disk or plate whose edges are sharp and can grip
or anchor against the sidewalls of housing 920 to prevent movement in the
direction opposite to the concavity.

[0098]One end of housing 920 is sealed with a stopper 940 such that liquid
fuel component chamber 944 is defined by stopper 940, housing 920 and
piston 980. Stopper 940 is made of any material capable of sealing
housing 920 against the escape of gas produced during reaction or liquid
fuel component 922, such as rubber, silicone or the like. Liquid fuel
component 922 preferably entirely fills liquid fuel component chamber
944. Further, liquid fuel component 922 may be pressurized with hydrogen
or a similar fuel gas so that the flow of liquid fuel component 922 out
of liquid fuel component chamber 944 is enhanced. The pressurized gas may
be contained in an elastic bladder disposed within liquid fuel component
chamber 944 and configured to expand to expel liquid fuel component 922
from liquid fuel component chamber 944. Optionally, a check valve or
pressure relief valve (not shown) is provided in the sidewalls of housing
920 which define liquid fuel component chamber 944 that allows air or
other environmental gases into liquid fuel component chamber 944 to
prevent a vacuum from forming therewithin and possibly stopping the
motion of piston 980.

[0099]The opposite end of housing 920 includes a second stopper 935 which
is similar in construction and materials as stopper 940. As such,
reaction chamber 918 is defined by second stopper 935, housing 920 and
piston 980. However, a valve 934 is disposed in second stopper 935 to
create a flow path to the fuel cell (not shown) or a conduit leading to
the fuel cell (not shown). Valve 934 is similar to other valves discussed
herein and is preferably a shut-off valve or a check valve configured to
open only when the pressure within reaction chamber 918 reaches a
threshold level. Solid fuel component 924 is disposed on the sidewalls of
housing 920 within reaction chamber adjacent to or near second stopper
935. Preferably, solid fuel component 924 is in a tablet-like form
pressed to or otherwise adhered to the sidewalls of housing 920 to form a
ring-like structure. Alternatively, solid fuel component 924 may be in
granular or powder form and held into place against the sidewalls of
housing 920 by a mesh or screen whose pore size is selected such that the
granules of solid fuel component 924 may not pass through the pores, but
which allows liquid fuel component 922 to pass therethrough to react with
solid fuel component 924.

[0100]A fluid transfer tube 982 is provided through piston 980 to fluidly
connect liquid fuel component chamber 944 with reaction chamber 918.
Fluid transfer tube 982 may be any type of tubing or pipe capable of
transferring liquid fuel component 922 to solid fuel component 924.
However, fluid transfer tube 982 is preferably a small-bore, rigid tube
made from a material which is substantially inert to liquid fuel
component 922, solid fuel component 924 and the gas produced by the
reaction therebetween. Preferably, the bore of fluid transfer tube 982 is
between about 0.001 inches and 0.01 inches; more preferably, the bore of
fluid transfer tube 982 is about 0.005 inches.

[0101]The length of fluid transfer tube 982 is selected such that the
movement of piston 980 toward stopper 940 results in only a drop of fluid
being expelled from the end of fluid transfer tube 982 onto solid fuel
component 924. Fluid transfer tube 982 preferably has sufficient length
such that when in an initial position, the free end of fluid transfer
tube 982 extends through solid fuel component 924 to a point at or near
second stopper 935. As such, when piston 980 moves, fluid transfer tube
982 is moved to a fresh supply of solid fuel component 924. Also, in the
alternative, piston 980 does not necessarily move, such as if liquid fuel
component 922 is pressurized with a bladder filled with a liquefied
hydrocarbon provided within liquid fuel component chamber 944. In such a
case, the liquefied hydrocarbon expands at constant pressure to expel
liquid fuel component 922 from liquid fuel component chamber 944.

[0102]In operation, the flow of liquid fuel component 922 is initially
triggered, such as by a user pressurizing liquid fuel component 922 or
puncturing or removing a seal covering the free end of fluid transfer
tube 982 (not shown). Liquid fuel component 922 then flows through fluid
transfer tube 982 into reaction chamber and drops onto solid fuel
component 924. Liquid fuel component 922 and solid fuel component 924
react to produce hydrogen. When sufficient pressure builds within
reaction chamber 918, check valve 934 opens to allow the fuel gas to flow
to the fuel cell (not shown) or, alternatively, a user or a controller
opens shut-off valve 934. If the pressure within reaction chamber 918
increases further, a reaction chamber pressure P918 eventually
reaches a level where reaction chamber pressure P918 pushes piston
980 toward stopper 940. However, additional increase in reaction chamber
pressure P918 will eventually prevent additional liquid fuel
component 922 from flowing through fluid transfer tube 982, as when
reaction chamber pressure P918 is greater than liquid fuel component
chamber pressure P944, liquid fuel component 922 cannot flow into
reaction chamber 918 due to the pressure gradient. In other words, the
liquid fuel component chamber pressure P944 needs to be higher than
the reaction chamber pressure P918 by at least a fixed amount, such
as X psi. Fluid transfer tube 982 is preferably sufficiently long such
that X equals 2 psi, for example, for fluid to flow through fluid
transfer tube 982. When reaction chamber pressure P918 is lowered,
such as by transfer out of reaction chamber through valve 934, liquid
fuel component 922 again flows through fluid transfer tube 982 so that
additional gas may be produced. In other words, so long as the produced
hydrogen is carried out of gas generating apparatus 912 at a rate
sufficient to keep reaction chamber pressure P918 relatively low,
liquid fuel component 922 continues to be transported to reaction chamber
918.

[0103]Some examples of the fuels that are used in the present invention
include, but are not limited to, hydrides of elements of Groups IA-IVA of
the Periodic Table of Elements and mixtures thereof, such as alkaline or
alkali metal hydrides, or mixtures thereof. Other compounds, such as
alkali metal-aluminum hydrides (alanates) and alkali metal borohydrides
may also be employed. More specific examples of metal hydrides include,
but are not limited to, lithium hydride, lithium aluminum hydride,
lithium borohydride, sodium hydride, sodium borohydride, potassium
hydride, potassium borohydride, magnesium hydride, calcium hydride, and
salts and/or derivatives thereof. The preferred hydrides are sodium
borohydride, magnesium borohydride, lithium borohydride, and potassium
borohydride. Preferably, the hydrogen-bearing fuel comprises the solid
form of NaBH4, Mg(BH4)2, or methanol clathrate compound
(MCC) is a solid which includes methanol. In solid form, NaBH4 does
not hydrolyze in the absence of water and therefore improves shelf life
of the cartridge. However, the aqueous form of hydrogen-bearing fuel,
such as aqueous NaBH4, can also be utilized in the present
invention. When an aqueous form of NaBH4 is utilized, the chamber
containing the aqueous NaBH4 also includes a stabilizer. Exemplary
stabilizers can include, but are not limited to, metals and metal
hydroxides, such as alkali metal hydroxides. Examples of such stabilizers
are described in U.S. Pat. No. 6,683,025, which is incorporated by
reference herein in its entirety. Preferably, the stabilizer is NaOH.

[0104]The solid form of the hydrogen-bearing fuel is preferred over the
liquid form. In general, solid fuels are more advantageous than liquid
fuels because the liquid fuels contain proportionally less energy than
the solid fuels and the liquid fuels are less stable than the counterpart
solid fuels. Accordingly, the most preferred fuel for the present
invention is powdered or agglomerated powder sodium borohydride.

[0105]According to the present invention, the fluid fuel component
preferably is capable of reacting with a hydrogen-bearing solid fuel
component in the presence of an optional catalyst to generate hydrogen.
Preferably, the fluid fuel component includes, but is not limited to,
water, alcohols, and/or dilute acids. The most common source of fluid
fuel component is water. As indicated above and in the formulation below,
water may react with a hydrogen-bearing fuel, such as NaBH4 in the
presence of an optional catalyst to generate hydrogen.

X(BH4)y+2H2O→X(BO)2+4H2

Where X includes, but is not limited to, Na, Mg, Li and all alkaline
metals, and y is an integer.

[0106]Fluid fuel component also includes optional additives that reduce or
increase the pH of the solution. The pH of fluid fuel component can be
used to determine the speed at which hydrogen is produced. For example,
additives that reduce the pH of fluid fuel component result in a higher
rate of hydrogen generation. Such additives include, but are not limited
to, acids, such as acetic acid and sulfuric acid. Conversely, additives
that raise the pH can lower the reaction rate to the point where almost
no hydrogen evolves. The solution of the present invention can have any
pH value less than 7, such as a pH of from about 1 to about 6 and,
preferably, from about 3 to about 5.

[0107]In some exemplary embodiments, fluid fuel component includes a
catalyst that can initiate and/or facilitate the production of hydrogen
gas by increasing the rate at which fluid fuel component reacts with a
fuel component. The catalyst of these exemplary embodiments includes any
shape or size that is capable of promoting the desired reaction. For
example, the catalyst may be small enough to form a powder or it may be
as large as the reaction chamber, depending on the desired surface area
of the catalyst. In some exemplary embodiments, the catalyst is a
catalyst bed. The catalyst may be located inside the reaction chamber or
proximate to the reaction chamber, as long as at least one of either
fluid fuel component or the solid fuel component comes into contact with
the catalyst.

[0108]The catalyst of the present invention may include one or more
transitional metals from Group VIIIB of the Periodic Table of Elements.
For example, the catalyst may include transitional metals such as iron
(Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), platinum
(Pt), palladium (Pd), osmium (Os) and iridium (Ir). Additionally,
transitional metals in Group IB, i.e., copper (Cu), silver (Ag) and gold
(Au), and in Group IIB, i.e., zinc (Zn), cadmium (Cd) and mercury (Hg),
may also be used in the catalyst of the present invention. The catalyst
may also include other transitional metals including, but not limited to,
scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr) and manganese
(Mn). Transition metal catalysts useful in the present invention are
described in U.S. Pat. No. 5,804,329, which is incorporated by reference
herein in its entirety. The preferred catalyst of the present invention
is CoCl2.

[0109]Some of the catalysts of the present invention can generically be
defined by the following formula:

MaXb

[0110]wherein M is the cation of the transition metal, X is the anion, and
"a" and "b" are integers from 1 to 6 as needed to balance the charges of
the transition metal complex.

[0113]In some exemplary embodiments, the optional additive, which is in
fluid fuel component and/or in the reaction chamber, is any composition
that is capable of substantially preventing the freezing of or reducing
the freezing point of fluid fuel component and/or solid fuel component.
In some exemplary embodiments, the additive can be an alcohol-based
composition, such as an anti-freezing agent. Preferably, the additive of
the present invention is CH3OH. However, as stated above, any
additive capable of reducing the freezing point of fluid fuel component
and/or solid fuel component may be used.

[0114]Other embodiments of the present invention will be apparent to those
skilled in the art from consideration of the present specification and
practice of the present invention disclosed herein. It is intended that
the present specification and examples be considered as exemplary only
with a true scope and spirit of the invention being indicated by the
following claims and equivalents thereof.

[0115]While it is apparent that the illustrative embodiments of the
invention disclosed herein fulfill the objectives of the present
invention, it is appreciated that numerous modifications and other
embodiments may be devised by those skilled in the art. For example, any
of the valves herein may be triggered by an electronic controller such as
a microprocessor. Further, in those embodiments including both a check
valve (34, 234, 334, 434, 534, 634, 834, 934) and/or a shut-off valve
(36, 834, 934), one or both of the valves may be omitted and/or the check
valve and shut-off valve may be interchanged. Additionally, feature(s)
and/or element(s) from any embodiment may be used singly or in
combination with feature(s) and/or element(s) from other embodiment(s).
Therefore, it will be understood that the appended claims are intended to
cover all such modifications and embodiments, which would come within the
spirit and scope of the present invention. All publications discussed
herein, including but not limited to patents, patent applications,
articles, and books, are incorporated by reference in their entireties.